Evaluating the In vitro performance of sweetpotato varieties with varying reverting potentials from virus infections
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The productivity of sweetpotato is largely constrained by virus infections. A resistance mechanism through reversion from virus infections can be exploited by rapidly micropropagating sweetpotato varieties with reversion potential for the production of clean planting material. However, in vitro micropropagation techniques had up to now not been used for the multiplication of virus-reverting sweetpotato genotypes. This study was carried out to establish the optimum MS media composition for micropropagation of sweetpotato genotypes with virus reversion trait. Two node cuttings from young sweetpotato stems of three sweetpotato varieties New Kawogo, NASPOT 8 and NASPOT 9 with high reversion potential were used. Nodal cuttings were thoroughly sterilized and cultured for 4 weeks using full strength Murashige and Skoog (MS) and half strength MS basal medium, supplemented with Naphthalene acetic acid (NAA) and 6-benzyl amino purine (BAP) concentration (mg/l) combinations of 0.0 and 0.0, 1.0 and 0.0, 1.0 and 2.5, and 1.0, and 5.0, respectively. Full strength MS medium supported in vitro sweetpotato growth better than half strength MS medium. The mean number of shoots was highest (2.5423 shoots) for media supplemented with 1.0 mg/l NAA and 2.5 mg/l BAP, and lowest (1.6215 shoots) for media without hormones. The mean length of shoots was highest (2.99 cm) for media supplemented with 1 mg/l NAA and 0.0 mg/l BAP, and lowest (0.7274 cm) for media supplemented with 1.0 mg/l NAA and 5 mg/l BAP. Number of roots per plantlet was highest on New Kawogo for all hormone concentrations for full MS medium while NASPOT 8 had the highest number of roots for all hormone concentrations for half MS medium. Overall, root development occurred better in media without auxins. The ability to rapidly micropropagate sweetpotato varieties with virus reversion potential provide an option for sweetpotato virus diseases management through dissemination of clean virus-resistant/reverting planting material.